Jet propulsion unit with cooling means for incoming air



June 26, 1962 R. s. RAE 3,040,519

JET PROPULSION UNIT WITH 000mm; MEANS FOR INCOMING AIR Filed Aug. 15,1954 2 Sheets-Sheet 1 FAA/001. PH J4MUL RAE,

IN V EN TOR.

June 26, 1962 R. s. RAE 3, 4

JET PROPULSION UNIT WITH COOLING MEANS FOR INCOMING AIR Filed Aug. 15,1954 2 Sheets-Sheet 2 FAA/paw, J/l/w/zz /?,4,

INVENTOR.

ArroxP/vzy aircraft.

The Garrett Corporation, Los Angeles, 'Caiifl, a corporation ofCalifornia Filed Aug. 13, 1954, Ser. No. 449,704 10 Claims. (Cl.6tl--35.6)

This invention relates to a propulsion unit having means for cooling theair entering the unit and relatees more particularly to a propulsionunit in which a compressor is utilized to increase the pressure of thecooled air so that the unit can produce a jet reaction force.

Non-air breathing engines, such as disclosed in pending US. PatentApplication Serial No. 417,867 filed March 22, 1954 by Randolph SamuelRae, can be utilized to develop power independently of the surroundingatmosphere so that the engine can be used to propel a craft, such as anaircraft, in mediums where practically no air is available. Asillustrated in US. Patent Application Serial No. 417,828 filed March 22,1954 by Randolph Samuel Rae, such an engine can propel an aircraft bydriving acompressor to produce a jet stream through a duct in which theengine is located. However, at high altitudes where the density of theair is low, it is necessary to expend a considerable amount of work onthe atmosphere by the compressor in order to compress a sufficientlylarge amount of air in order to propel the It is therefore proposed bythe present invention to cool the air entering the propulsion unit sothat for a given compressor discharge pressure, the engine will have todo less work on the air entering the unit. This initial cooling can beaccomplished by cooling means positioned in the entrance to the duct andthe cooling means can be supplied with the low temperature fuel supplyfor the engine.

It is therefore an object of the present invention to provide apropulsion unit for propelling an aircraft, which unit is the form of aduct containing a compressor and a cooling unit located ahead of thecompressor to cool the air entering the compressor.

Another object of the invention is to provide a propulsion unit in whichthe air leaves the propulsion unit in a jet stream and in which the airentering the propulsion unit is cooled by a low temperature fluid supplyin order to reduce the work on the compressor for a given mass flow ofair.

Another object of the invention is to provide a propulsion unit drivenby a non-air breathing engine operated on low temperature fuel andoxidant and in which th low temperature fuel is utilized to cool the airentering the propulsion unit. 7

These and other objects of the invention not specifically set forthabove will become readily apparent from the accompanying description anddrawings in which;

FIGURE 1 is a diagrammatic view of the propulsion unit illustrating theconstruction of one form of non-air breathing engine that can beutilized with the invention.

FIGURE 2 is a physical form of the propulsion unit showing the coolingunit located ahead of the compressor which is driven by the non-airbreathing engine.

FIGURE 3 is a vertical section along line 3-3 of FIG- URE 2 illustratingthe construction of the cooling unit located ahead of the compressor.

FIGURE 4 is a view similar to FIGURE 3, partly in section and withportions cut away to show the mounting for the engine and theconstruction of the cooling coils.

One form of non-air breathing engine which can be utilized in connectionwith the invention is illustrated in FIGURE 1 and has a storage tank 5for the engine fuel,

atent 'ice which fuel can be in the form of a low temperature liquid orgas. The fuel tank 5 is connected to'the cooling unit 6 through passage7 and pump 8 and the discharge from the cooling unit is connected to theouter chamber 9 of heat exchanger unit 10 through passage 11. Chamber 9is also connected to a first combustion chamber 12 through a passage 13in order to supply fuel to the combustion chamber. The oxidant for thefuel is stored in a tank 14 which is connected to the outer chamber 15of heat exchanger 16 through a passage 17 and a pump 18, and thedischarge from outer chamber 15 connects with the passage 19. A passage20 connects passage 19 to combustion chamber 12 and passage 20 containsa valve 21 for controlling the amount of oxidant supplied to thecombustion chamber to combust a portion of the fuel. The portion of thefuel in passage 13' which is combusted in chamber 12 determines thetemperature in passage 22 which connects the first stage 23 of theengine with the chamber 12. Stage 23 exhausts to a second combustionchamber 24 througha' passage 25 and this second combustion chamber islikewise connected to passage 19 through a passage 26 containing a valve27 in order to regulate the amount of oxidant directed to combustionchamber 24. In combustion chamber 24, a further amount of fuel will becombusted and this chamber connects with a secondstage 28 through apassage 29. The exhaust from the second stage 28 connects with the thirdcombustion chamber.30 through passage 31 and this combustion chamber isalso connected with passage 19 through a passage 32 containing the valve33. The combustion chamber '30 connects with a third stage 34 throughpassage 35 and stage 34 exhausts to passage 36 which passage leadsthrough the central chambers 37 and 38 of heat exchangers 16 and 10,respectively, and to afterburner 39 of the engine which will presentlybe described.

As indicated diagrammatically in FIGURE 1, the output shafts of all thestages are shown connected to a common shaft 40 and it is understoodthat additional stages can be added to the engine as indicated by thedotted passage extensions in FIGURE 1. While the stages have beenillustrated as turbines, other types of gas expansion engines can beutilized for any one or more of the stages. The amount of fuel combustedin each of the combustion chambers 12, 24 and 30 will depend upon thesetting of the valves 21, 27 and 33, respectively, and suihcient fuelwill be combusted in each combustion chamber to raise the inlettemperature to its-corresponding stage to approximately the maximumwhich can be withstood by the construction'rnaterials of each stage. Anysuitable type of liquid or gas can be utilized as fuel by the engine,such as liquid hydrogen, gasoline, methane, acetylene, alcohol and thelike, and the fuel can be combusted with any suitable oxidant, such asair, oxygen, hydrogen peroxide, nitric acid, etc. in either the liquidor gaseous phase. When liquid hydrogen is utilized as the fuel supplyand liquid oxygen as the oxidant, heat exchangers 10 and 16 serve toincrease the temperature of the hydrogen and oxygen in order to increasethe chiciency of the cycle.

The common output shaft 44? is connected to a cornpressor 41 and bothcompressor 41 and the afterburner 39 are located within duct 42 of thepropulsion unit. Upon rotation of the compressor by the engine, thepressure of the air entering the duct will be greatly increased and theexit of this high pressure air from the exit nozzle end 43 of the ductwill result in a jet reaction force upon the duct itself. Since passage36 contains some fuel which is not combusted in the combustion chambers,this fuel can be combusted in the afterburner with a portion of airflowing thr-ough the duct in order to provide added thrust from thepropulsion unit.

A physical form of the propulsion unit is illustrated in FIGURES 2through 4 wherein like reference numerals represent like parts as in theprevious description. The engine is contained in body member 44 which iscentrally located with the duct 42 by means of four struts 45. Fuelpassage 7 supplies fuel to the cooling unit 6 and to passage 11 whichpasses through one of the struts 45 to heat exchanger 10. Passage 13connects heat exchanger with the combustion chamber 12 for the firststage 23 of the engine. The combustion chamber 12 is connected bypassage 22 with the manifold 46 for the first stage 23 and the manifold46 has two inlet passages 47. Passage 29 connects combustion chamber 24with inlet manifold 48 having four inlet passages 49 for the secondstage 28 and passage connects combustion chamber 30 to an inlet manifold50 having eight inlet passages 51 for the third stage 34. The exhaustfrom stage 34 is passed through heat exchangers 10 and 16 to theafterburner 39. Oxidant is supplied by passage 17 through one of thestruts 45 to the heat exchanger unit 16 and then to passage 19 whichsupplies the combustion chambers. The combustion chambers can be of anywell-known construction and can contain a screen having finely dividedplatinum particles thereon so that when the oxidant is directed againstthe platinum through a nozzle, the platinum acts as a catalyst tomaintain the flame.

The operation of the physical embodiment of the engine is the same asdescribed previously for the diagrammatic form of the invention and thevalves 21, 27 and 33 serve to regulate the oxidant supplied to eachcombustion chamber so as to regulate the amount of fuel combusted ineach combustion chamber. Each stage of the physical form is illustratedas a helical flow turbine of well known construction and it isunderstood that the turbines are all connected to a common drive shaftas illustrated in FIGURE 4. Because of the increased number of inletpassages to each succeeding stage of the engine, it is apparent that theexpanded exhaust volume from each turbine can be handled by thesucceeding turbine. Each of the helical flow turbines can be supportedby brackets 81 positioned on opposite sides of the turbine and securedto body member 44 so that the turbines are held rigidly in positionwithin the body.

The common shaft 40 connects with a substantially conical nose section57 which has support webs 58 and a central member 59 for receiving theend of shaft Section 57 carries a circular hub member 66 to which aresecured two rows of axial flow compressor blades 61 and 62 and two rowsof stationary blades 63 and 64 are supported by circular hubmember 65which is secured to the duct 42. The row of stationary blades 63 ispositioned between blades 61 and 62 while the row of stationary blades64 is positioned aft of blades 62. Since the blades 61 and 62 arerotated at high speed by the non-air breathing engine, the air enteringthe entrance 66 of duct 42 is compressed to a high pressure and whenthis high pressure air expands through the nozzle end 43 of the duct,the duct receives a reaction force serving to propel the aircraft onwhich the duct is mounted. The axial flow compressor, comprised of themovable blades 61 and 62 and the stationary blades 63 and 64, can he ofany well known design and additional rows of blades can be utilized ifdesired. The base portion of nose section 57 covers the forward end ofthe body member 44 so that the section 57 and the body member 44 form acontinuous, streamlined surface within the interior of the duct.

Since the passage 36 connected with the last stage 34 of the turbinecontains a portion of the fuel, it is possible to ignite the remainingfuel in the afterburner 39 with the high pressure air in duct 42 andthus increase the temperature of the air leaving nozzle 43. A circularV-shaped ring 52 is positioned between duct 42 and body member 44 and issupported by struts 53. Four cone members 54 are located at theintersection of ring 52 with the struts 53 and a flame holder 55 issupported across the open end of each of the members 54. The flameholders 55 carry a deposit of finely divided platinum which serves as acatalyst to maintain the burning of the fuel within the duct 42. Theexhaust passage 36 is connected to a plurality of tubes 56 whichterminate at each of the cone members 54 in order to supply theremaining fuel to the catalyst so that it can be ignited with highpressure air being driven through passage 42 and thus raise thetemperature of this air and increase the thrust caused by the expansionof the air out of the nozzle end 43.

Referring now to the construction of cooling unit 6 which serves to coolthe air entering the duct 43 and compressor 41, a circular member 67 ispositioned between the body of duct 42 and its entrance portion 66 andsupports the entrance portion by bolts 67'. The member 67 carries anumber of cooling fins 63 which project inwardly towards the nosesection 57 and a number of helical cooling tubes 63 pass through thesecooling fins and are supported thereby. Member 67 also has an entranceheader 70 which connects passage 7 with each of the helical tubes 69 andhas a discharge header 71 which receives the fuel discharged from eachone of the tubes 69. This discharge header connects with the passage 11which supplies fuel to the stages of the non-air breathing engine. Thus,it is seen that the low temperature fuel supplied by passage 7circulates through the cooling coils of unit 6 and thereby cools the airentering the inlet 66 of duct 42. Since the air is cooled before itenters the compressor, it is understood that the compressor will have todo less work on the air to obtain a given discharge pressure and massflow. In other Words, by utilizing the cooling unit 6 in connection withthe compressor, it is possible to use an engine of smaller output toobtain a given discharge pressure and a given propulsion unit output.

When low temperature liquid hydrogen is carried as the fuel by tank 5,the hydrogen supplied by pump 8 to the cooling unit will be at atemperature slightly above liquification temperature of hydrogen becauseof the work done on the hydrogen by the pump. Since the hydrogen entersat the aft side of the cooling unit and leaves at the forward side ofthe cooling unit, the hydrogen gas passing the the engine from header 31will be at about ambient temperature and considerable cooling of the airentering the compressor results. Also, if low temperature liquid oxygenis carried by tank 14, the oxygen instead of the hydrogen could bepassed through cooling unit 6 on its way to heat exchanger 16 so thatthe incoming air would be cooled by the low temperature oxygen. Thecooling unit 6 can also be utilized when other low temperature fuels andoxidants are used by the engine.

In operation of the present invention, it is understood that the enginecomprised of stages 23, 28, 34 drive the common shaft 40 which, in turn,will rotate the blades 61 and 62 of the compressor in order to develop ahigh pressure within the duct 42 and that the air entering thecompressor will be cooled by the cooling unit 6 so that the work load onthe compressor for a given discharge pressure will be reduced. The aircompressed by the axial flow compressor will be raised in temperature bythe combustion of the fuel in the exhaust from the last stage 34 of theengine. Thus, a high temperature, high pressure jet will exist at thenozzle end 43 of the duct 42, which jet can be, utilized for propellingthe craft which mounts the propulsion unit.

By the present invention, a propulsion unit is provided in which acompressor and an engine are mounted within a duct to produce a jetthrust. The type of engine described can be very small and compact whenlow temperature liquid hydrogen and oxygen are used as the fuel andoxidant, respectively. A portion of the hydrogen fuel is utilized as adiluent or working fluid of high specific heat for the engine and thisportion is available for the afterburne'r. Various other types ofnon-air breathing engines can be utilized in connection with theinvention and these engines can utilize various substances as fuel andoxidant. Also, other construction of cooling units can be positionedahead of. the compressor. Various other modifications are contemplatedby those skilled in the art without departing from the spirit and scopeof the invention as herein defined by the appended claims.

What is claimed is:

' 1. A propulsion unit for producing a jet reaction force for anaircraft comprising a passage means having a nozzle at the exit end,power means positioned within said passage means :andutilizing a lowtemperature substance as fuel and a low temperature substance as anoxidant, the temperature ofsaid substances being below the temperatureof atmospheric air entering said passage means,

compressor means located within said passage means and connected to saidpower means for increasing the pressure of the air entering said passagemeans, and cooling means located within said passage means forwardly ofsaid compressormeans for cooling all the air entering said passagemeans, and means for conducting one of said low temperature substancesthrough said cooling means onits way to said power means, said powermeans being operative solely'by said'low temperature fuel and oxidantand independently'of the air entering said passage means. I

2. A propulsion unit for propelling an aircraft by creating a jetthrust, comprising a duct having a nozzle exit, an engine supportedwithin said duct by struts and operable independently of the mediumsurrounding the aircraft, a supply of low temperature hydrogen as thefuel for the engine and a supply of low temperature oxygen as theoxidant for the engine, a compressor located within the duct andconnected to said engine in order to compress the air entering the inletto said duct, cooling means located forwardly of said compressor forcooling all the incoming air prior to being compressed, and means forconnecting said cooling means to said engine and to one of said suppliesso that hefore entering said engine said one supply provides a coolingmedium for the incoming air.

3. A propulsion unit as defined in claim 2 wherein said cooling means isconnected to said hydrogen supply and said cooling means dischargeshydrogen gas to said englue.

4. A jet propulsion unit comprising passage means having an inlet foratmospheric air at one end and an exit nozzle at the opposite end,compressor means located within said passage means for compressingatmospheric air entering said passage means and discharging said airthrough said exit nozzle, power means for driving said compressor means,a supply of a low temperature substance for use as fuel for said powermeans and a supply of low temperature substance for use as thesole-oxidant for fuel supplied to said power means, the temperature ofsaid substances being below the temperature of atmospheric air enteringsaid passage means, heat exchanger means located in said passage meansforwardly of said compressor means, means for introducing one of saidlow temperature substances to said heat exchanger means to cool all theatmospheric air entering said inlet and to increase the temperature ofsaid one substance, means for discharging said one substance from saidheat exchanger means to said power means, means for connecting the otherof said substances to said power means, said power means comprisingcombusting means for com busting only a portion of the fuel supplied tosaid power means with a regulated amount of said oxidant to provideafuel-rich exhaust, and burner means located within said passage meansaft of said compressor means and connected only with said exhaust forcombusting the fuel remaining in said exhaust with the atmospheric airdischarged from.

said compressor means.

5. A jet propulsion unit comprising passage means having an inlet foratmospheric air at one end and an exit nozzle at the opposite end,compressor means located within said passage means for compressingatmospheric air entering said passage means and discharging said airthrough said exit nozzle, power means for driving said compressor means,a supply of low temperature fuel for said power means and a supply ofoxidant for the fuel supplied to said power means, the temperature ofsaid fuel being below the temperature of atmospheric air entering saidpassage means, heat exchanger means located in said passage meansforwardly of said compressor means for cooling all the incoming air,means for introducing said low temperature fuel to said heat exchangermeans tocool the atmospheric. air entering said inlet, means fordischarging said fuel from said heat exchanger means to said powermeans, means for connecting said oxidant to saidpower means, said powermeans comprising a plurality of expansion stages and combusting meansfor combusting only a portion of the fuel supplied to said power meanswith a regulated amount of said oxidant to provide a fuel-richexhaust,,and burner means located within said passage means aft of saidcompressor means and connected. with said exhaust as the only source offuel,

said burner means combusting the fuel remaining in said exhaust with theatmospheric air discharged from said compressor.

6. A jet propulsion unit comprising passage means having an inlet foratmospheric air at one end and an exit nozzle at the opposite end,compressor means located within said passage means for compressingatmospheric air entering said passage means and discharging said airthrough said exit nozzle, power means for driving said compressor means,a supply of low temperature liquid hydrogen for use as fuel by saidpower means and a supply of oxidant for said power means, heat exchangermeans located in said passage means forwardly of said compressor means,means for connecting said hydrogen supply with said heat exchanger meansto cool the atmospheric air entering said inlet and to increase thetemperature of said hydrogen, means for discharging saidhydrogen fromsaid heat exchanger means to said power means, means for connecting saidoxidant to said power means, said power means comprising combustingmeans for combusting only a portion of the hydrogen supplied to saidpower means with a regulated amount of said oxidant to provide ahydrogen rich exhaust, and burner means located within said passagemeans aft of said compressor means and connected with said exhaust asthe only source of fuel, said burner means combusting the hydrogen insaid exhaust with the atmospheric air discharged from said compressor.

7. A jet propulsion unit as defined in claim 6 wherein said power meansincludes a plurality of expansion stages, each of said stages receivinguncomhusted hydrogen as a working fluid of high specific heat, saidcombusting means increasing the entering temperature to each stage to amaximum temperature that can be withstood by each stage.

8. A jet propulsion unit comprising means forming a duct having an airinlet at one end and a reduced jet nozzle at the opposite end; a bodysupported in said duct forming means and co-operating therewith to givethe duct an annular configuration between said inlet and said nozzle; anengine in said body; compressor rotor means in the annular section ofsaid duct adjacent the forward portion thereof, said compressor rotormeans being connected for operation by said engine to compress airentering said inlet and direct it around said body and outwardly throughsaid nozzle; heat exchanger means in said duct between the inlet endthereof and said compressor rotor means for cooling all the air directedaround said body by said compressor rotor means, said heat exchangermeans having a fluid passage; a supply of fuel for said engine at atemperature lower than the temperature of air entering said inlet, andmeans for conducting said fuel to said fluid passage and from the latterto said engine.

9. A jet propulsion unit comprising inner and outer body means forming aduct having an inlet at one end, a jet nozzle at the other end and anannular intermediate portion progressingly decreasing in cross-sectionalarea toward the nozzle end; engine means wholly enclosed in said innerbody means; a compressor rotor adjacent the forward end of said annularintermediate portion, said compressor rotor being driven by said engineto draw air into said inlet and direct it through said annularintermediate portion to said nozzle; first and second heat exchangerseach having a pair of fluid passages, the first of said heat exchangersbeing disposed in said duct in advance of said compressor rotor to causeair drawn into said inlet to flow through one of the fluid passages insaid first heat exchanger; means for directing fuel through the otherfluid passage in said first heat exchanger and through one fluid passagein the second heat exchanger to said engine means; means for directingexhaust gases from said engine means through the second fluid passage ofsaid second heat exchanger; and burner means in the annular intermediateportion of said duct immediately in advance of said nozzle, said burnermeans receiving the exhaust gases following passage thereof through saidsecond heat exchanger.

10. A jet propulsion unit comprising means forming a duct'having aninlet at one end and a reduced jet nozzle at the other end; body meanssupported in said duct and serving to give the same an annularconfiguration between said inlet and said nozzle; engine means in saidbody means and operable to have a fuel-rich exhaust; compres-' sor rotormeans in the annular section of said duct adjacent the forward portionthereof, said compressor rotor means being connected for operation bysaid engine means to draw air into said inlet and direct it around saidbody means and outwardly through said nozzle; heat exchanger meanssurrounding said body means between said compressor rotor means and saidinlet for cooling all the air directed around said body means, said heatexchanger means having a fluid passage; fuel conducting means leadingfrom a low temperature source of fuel to the fluid passage in said heatexchanger means and from the latter to said engine means; annular burnermeans supported in the annular section of said duct adjacent the nozzleend thereof; and means for conducting the exhaust from said engine meansto said burner means in order to combust the fuel in said exhaust withthe air directed around said body means.

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